IPv6 radvd advise static IP as gateway?

I am running radvd (2.17-2, Debian Buster) on a local network to provide IPv6 access. I would like to make radvd advertise the static IP of the interface (e.g. 2001::1/64) as the gateway IP instead of the link-local address (like fe80::something/64). I have tried AdvRASrcAddress but it seems to be only effective for LL addresses so I can't specify 2001::1/64 there.

How to make radvd advertise the static IP as gateway instead of the LL address?

If radvd isn't up to this task, I'm open to other solutions.